clinton is waking up now in a new york hospital. she is being treated for a blood clot that formed after her fall and concussion that happened a few weeks ago. want to bring in dr. sanjay gupta, our chief medical correspondent. sanjay, explain this for us because, first of all, when you think about it, she developed this blood clot related to a concussion. you would think maybe the clot formed in the brain, but that's not necessarily the case. >> no, it's not necessarily the case. and i think saying it's related to the concussion, that may be putting that wrong impression possibly in people's minds. there's a really simple reason why, suzanne. she's being treated with blood thinners, or anti-coagulants. if this were a blood clot on top of the brain or around the brain, you wouldn't do that because that could worsen the bleeding and prevent an operation from being performed, if that is necessary. again, no one is saying that's the case here. you're absolutely right. the typical sort of blood clots that are treated with blood thinners are something known as dvt, for example, you may have h